Differential feed attachment means for shirring

ABSTRACT

A differential feed attachment means for a drop feed sewing machine, said attachment being intended to replace the conventional feed dogs and consisting of two feed dogs arranged in tandem with the front feed dog being adjustable through a lever system relatively to the rear feed dog so that the amount of travel of the front feed dog can be in unison with the rear feed dog and may be quickly and easily varied by the operator while the machine is in motion to continuously or intermittently gather or shirr material being operated upon.

United States Patent Edward L. Seaman 65 Harvard St., Garden City, N.Y. 11530 [21 1 Appl. No. 820,995

[22] Filed May 1,1969

[45] Patented May 18, 1971 [72] lnventor [54] DIFFERENTIAL FEED ATTACHMENT MEANS FOR SHIRRING 4 Claims, 8 Drawing Figs.

[52] US. Cl 112/208 [51] Int. Cl ....D05b 27/08 [50] Field of Search..... 112/208, 209

[5 6] References Cited UNITED STATES PATENTS 423,399 3/1890 Trowbridge 112/208 1,327,647 1/1920 Weis Primary ExaminerRichard J. Scanlan, Jr. Attorneys-Abraham Engel, Howard .1. Churchill, Robert S. Dunham, P. D. Henninger, Lester W. Clark, Gerald W.

Griffin and Thomas F. Moran ABSTRACT: A differential feed attachment means for a drop feed sewing machine, said attachment being intended to replace the conventional feed dogs and consisting of two feed dogs arranged in tandem with the front feed dog being adjustable through a lever system relatively to the rear feed dog so that the amount of travel of the front feed dog can be in unison with the rear feed dog and may be quickly and easily varied by the operator while the machine is in motion to continuously or intermittently gather or shirr material being operated upon.

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INVENTOR. 50m Z Jew/4 be operably for continuous gathering or for gathering only at desired intervals or places without stopping the machine.

A further object of the invention is to provide a differential feed attachment means as recited, which is relatively simple in construction, can be readily applied to a drop feed sewing machine and when applied is simple to use to vary the gathering ration and return to normal sewing without stopping the machine.

The foregoing and other objects of. the invention. not specifically enumerated, will become apparent from 7) detailed description which follows when considered in connection with the accompanying drawings, wherein:

FIG. I is a front elevation of the left-hand end of a sewing machine to which the differential feed attachment means of my invention is applied.

FIG. 2 is a partial end elevation as viewed in the direction of the arrows 2-2 on FIG. 1.

FIG. 3 is a fractional top plan view of FIG. 1 whereat the attachment means is applied.

FIG. 4 is an underside plan view as viewed in the direction I of the arrows 4-4 on FIG. I.

FIG. 5 is an enlarged view of FIG. 3 with the throat plate cut away and shows the feed dogs in retracted position during maximum shirring.

FIG. 6 is a view similar to FIG. 5 and shows the feed dogs in advanced operative position during maximum shirring.

FIG. 7 is a section taken substantially along the plane of the line 7-7 of FIG. 6.

FIG. 8 is a section taken along the plane of the line 8-8 of FIG. 1.

Referring to the several FIGS. of the drawings on which corresponding parts are designated by the same reference numerals, the differential feed attachment means is shown as applied to a conventional drop feed sewing machine, the lefthand head 10 of which has a reciprocative needle bar 12 which carries a needle I4, apresser foot bar 16 and a table or bed 18 from the underside of which is supported a .feed rock shaft 20 which operates a feed bar 22, a feed lifting rock shaft 24 and a bobbin case 26. The top face of the table is recessed as shown at 28 to provide a shoulder 30 onto which'a conventional throat plate is normally secured.

The differential feed attachment comprises a rriodified throat plate 32 which has conventional openings for the ricedle and feed dogs and is secured onto the shoulder 30 by screws 34. As herein shown, the throat plate 32 has a depending side plate 36 providedv at one edge 36a thereof, intermediate its length, with an inwardly extending lug 38 having a screw-threaded opening therein through which extends a thumb screw 40. At another edge 36b the side plate 36 has a protruding lug 42 leaving a threaded opening herein through which extends a thumb screw 44.

Pivotally mounted on a pin 46 at the lower end of the side plate is a flat bellcrank lever 48 having angularly disposed arms 48a and 48b. The upper end of arm 48a is angularly bent and bifurcated as shown at 48c. The ami 48b is formed with holes 48d 48e. Projecting from the side 36d of plate 36 is a tongue 50. Between a notch 51 near free end of said tongue and the hole 48e is secured helical tension spring 52. The hole 48d is adapted to accommodate one end of a chain or lever connected to a treadle (not shown). Pivotally mounted on a pin 54 extending downwardly from the underside of the throat plate 32 is an offset end 55 of a link 56. the opposite end 'of which has a depending cylindrical pin 58 which engages in the slot of the bifurcated end 48c of lever 48. Stop studs 59 and 60- depend also from the underside of throat plate 32 to limit the pivotal movement of the link 56.

Fixedly mounted on the feed bar 22 by screws 61 and 62 (FIGS. 4 and &) is a support plate 64 for a pair of feed dog members 66 and 68. The rear feed dog 66 is movable with the plate and the front feed dog 68 is slidable on said plate. For guiding the front feed dog 68 in its reciprocating movements, is a pair of pins 70 carried by the rear feed dog 66 and slidable in holes in the front feed dog 68. Surrounding the pins 70 and bearing againstconfronting shoulders on said feed dog members are helical tension springs 72.

Adjacent the froht end of the support plate 64 on a pin 76 fixedly carried thereby is pivotally mounted, intermediate its ends, a lever 78 one end portion 78a of which bears against the front end 'of dog 68 and the opposite end 78b of which is carried and is adapted to ride on the cylindrical pin 58 as said lever is pivoted on the pin 76 when the support plate is reciprocated by the movement of said plate by the feed bar 22. Also fixedly mounted on the support plate byscrews 80 is a spacer plate 82 which terminates rearwardly of the front end of the support plate to provide a shoulder 83 for limitingthe rearward movement of the lever 78. To hold the lever 78, during the movement, flat against the support plate, a flat leaf spring 84 is soldered to the top of the spacer plate.

In the operation of a machine to which the differential feed attachment means is applied, it will be apparent that when the thumb screw 40 is out of engagement with the arm 48a of the bellcrank lever 48, as shown by the broken lines in FIGS. 5 and 6, the curved end 78b of the lever 78 is out of engagement with the cylindrical pin 58 and the springs 72 hold the front dog 68 at its fully retracted position, and the tension spring 52 biases the bifurcated end 48c of the bellcrank lever to hold the link 56 against the stop stud 59, hence during reciprocation of the dog-supporting plate 64 by the feed bar 22, the front and rear dogs will move in unison to provide normal feed for the machine and no shirring will take place. when the thumbscrew is moved inwardly against the arm 48a against the tension of spring 52, the bifurcated end 480 of the lever moves the cylindrical pin 58 on the link 56 into engagement with and over the curved end portion 78b of lever 78 to a limiting position against the stud 60 as shown in FIGS. 5 and 6. In last stated position or at an intermediate position of the link 56, the lever 78 will rock on the pin 58 as the lever 78 is reciprocated on the pin 76 during the movement of the support plate 64 to a limiting position on its rearward stroke by engagement with the shoulder 83 as shown in FIG. 5. During the forward movement of the supporting plate it will thus be seen that the front dog will move relatively to and more rapidly than the rear dog. Because of this relative movement of the dogs, a shining of the material being operated upon will take place. The degree of shirring may be varied in the ratio up to l to 3 depending upon the position of pin 58. Adjustment of the th'umbscrew 44 in relation to the bellcrank arm 48b is utilized where it is desired to alternate shirring with the normal "sewing operation, i.e., if during normal sewing it is desired to shirr a portion of the material being acted upon, by pressing on the treadle (not shown) the pin 58 can be moved over the curved end 78b of lever 78 to provide the desired degree of shirring. By releasing pressure of the treadle normal sewing is resumed.

While I have shown and described a prepared embodiment of the invention, it is to be understood that changes in the specific construction disclosed may be made within the range of mechanical or engineering skill without departing from the spirit of the invention as hereinafter claimed.

I claim:

1. A differential feed attachment means for use on a drop feed sewing machine and intended to replace the conventional feed dog, comprising a front feed dog and a rear feed dog arranged in tandem and capable of movement in unison and of movement relative to one another, a support, plate reciprocable by the feed rock shaft of the machine and upon which support plate the feed dogs are mounted, an interrelated lever system of varying the amount of travel forwardly of the front dog in relation to the rear dog and manually adjustable means for controlling the positions of the levers in said lever system, the lever system comprising a bellcrank lever, a pivoted link operable by the bellcrank lever, a second lever pivoted between its ends on the support plate and cooperable at one end with said link and at its other end with said front feed dog to control the amount of travel of the front feed dog, spring means normally biasing the bellcrank lever to a position to cause movement in unison of the front feed dog and the rear feed dog, and wherein the manually adjustable means is operable to vary the position of the bellcrank lever to cause movement of the front feed dog more rapidly than the rear feed dog.

2. A differential feed attachment means according to claim 1, wherein the lever system is carried by a throat plate and a side plate depending from said throat plate, the bellcrank lever is pivoted to said side plate, the upper end of one arm of said lever is bifurcated, the link is pivoted at one end to the underside of the throat plate and the other end of the link has a pin engaging in the bifurcated end of the bellcrank lever and the second lever engages said pin, whereby the degree of movement of the front feed dog is determined by the engagement position of the pin on the second lever.

3. A differential feed attachment according to claim 2, wherein the manually adjustable means is carried by the side plate for engagement with an arm of the bellcrank lever to vary the position thereof.

4. A differential feed attachment means according to claim 2, wherein a manually adjustable stop means is carried by the side plate for engagement with an arm of the bellcrank lever and said arm of the bellcrank lever is movable by a treadle into the engagement with said stop means during operation of the machine to change from a normal sewing operation to a shirring operation.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,57 ,7 9 Dated M y 97 Inventor( EDWARD L. SEAMAN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 13, "operably" should read operable ----5 line 19, change "ration" to ratio line 22, "7)" should read the Column 2, line 6, change "8a" to 7 line 63, change "of" (second occurrence) to Column 3, line 3, change "of" (first occurrence) to for Signed and sealed this 2nd day of November I 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents TORM PO'WSO (10-69) USCOMM'DC seam-ps9 a 1.5. GOVERNMENT PHIN'ING OFFCE 959 0-366-3315 

1. A differential feed attachment means for use on a drop feed sewing machine and intended to replace the conventional feed dog, comprising a front feed dog and a rear feed dog arranged in tandem and capable of movement in unison and of movement relative to one another, a support plate reciprocable by the feed rock shaft of the machine and upon which support plate the feed dogs are mounted, an interrelated lever system of varying the amount of travel forwardly of the front dog in relation to the rear dog and manually adjustable means for controlling the positions of the levers in said lever system, the lever system comprising a bellcrank lever, a pivoted link operable by the bellcrank lever, a second lever pivoted between its ends on the support plate and cooperable at one end with said link and at its other end with said front feed dog to control the amount of travel of the front feed dog, spring means normally biasing the bellcrank lever to a position to cause movement in unison of the front feed dog and the rear feed dog, and wherein the manually adjustable means is operable to vary the position of the bellcrank lever to cause movement of the front feed dog more rapidly than the rear feed dog.
 2. A differential feed attachment means according to claim 1, wherein the lever system is carried by a throat plate and a side plate depending from said throat plate, the bellcrank lever is pivoted to said side plate, the upper end of one arm of said lever is bifurcated, the link is pivoted at one end to the underside of the throat plate and the other end of the link has a pin engaging in the bifurcated end of the bellcrank lever and the second lever engages said pin, whereby the degree of movement of the front feed dog is determined by the engagement position of the pin on the second lever.
 3. A differential feed attachment according to claim 2, wherein the manually adjustable means is carried by the side plate for engagement with an arm of the bellcrank lever to vary the position thereof.
 4. A differential feed attachment means according to claim 2, wherein a manually adjustable stop means is carried by the side plate for engagement with an arm of the bellcrank lever and said arm of the bellcrank lever is movable by a treadle into the engagement with said stop means during operation of the machine to change from a normal sewing operation to a shirring operation. 